The hepatic lobule is the basic structural and functional unit of the liver, consisting of plates of hepatocytes radiating from a central vein. Bile canaliculi, sinusoids, and portal triads are key features. Nephrons are kidney units, alveoli lung units, islets pancreatic endocrine units.
Explanation:
The Cell Theory, one of the fundamental principles of biology, was proposed by Matthias Schleiden (a German botanist) in 1838 and Theodor Schwann (a British zoologist) in 1839. Schleiden concluded that all plants are composed of cells, and Schwann extended this to animals. Rudolf Virchow later added the third tenet in 1855: 'Omnis cellula e cellula' (all cells arise from pre-existing cells).
Explanation:
The hypothalamus contains numerous nuclei, each with specific functions. The supraoptic nucleus (SON) and the paraventricular nucleus (PVN) are large neurosecretory nuclei located in the anterior hypothalamus. The supraoptic nucleus primarily synthesizes Antidiuretic Hormone (ADH, or vasopressin), while the paraventricular nucleus primarily synthesizes Oxytocin (though both nuclei produce both hormones in smaller amounts). These hormones are transported down the axons of these neurons and stored in the posterior pituitary for release into the bloodstream.
Explanation:
Guttation is the exudation of water droplets from hydathodes, driven by root pressure under high humidity and low transpiration conditions.
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